how to remove old file versions from a wss 3.0 document library

Hello Expert
have some problems with my wss 3.0 sp2 content db, is currently over 160 GB.
i found out that many doc libraries are using:
- create major versions  (only, without limit the number)

i'm setting "no versioning" on most of them but i'm wondering if there is a quick way to delete, remove the old file versions keept and leave only the last published?

thanks for your help. -andrea